For parts I would always keep in mind your local Kymco dealer (or a dealer that sells online). Some items in the future may need to be OEM. For other parts (hoses, bulbs, brake pads, rollers/sliders, filters, bearings, levers, etc.) you can do a Google search for scooter parts. I just did and large number of online retailers show up.
In your particular case, where there are not many People S 150 scooters around, you'll want to dig deeper into the sites to see if they list your specific model of scoot.
I clicked on scooterpartsco.com, Kymco and then under People S 150. It listed a number of parts. Some look to be interchangeable with other Kymco 125/150/200 cc models.
I think this question gets asked a lot on internet forums...which is best?...but there are so many variables. Usually you have to find a site that has your needed part and then compare prices with another site or 2 or three.
ebay and Amazon are also viable options for many parts.
It seems like Kymcos are very well made and the only items you usually need are a belt, brake pads, air filter and spark plug to keep you going for many miles.
